Accession Number:

AD0705576

Title:

DRAG MEASUREMENT IN A LOW DENSITY GAS STREAM

Descriptive Note:

Final rept. 14 Apr-26 Sep 1969

Corporate Author:

ARNOLD ENGINEERING DEVELOPMENT CENTER ARNOLD AFB TN

Personal Author(s):

Report Date:

1970-05-01

Pagination or Media Count:

35.0

Abstract:

Two methods of measuring the drag of bodies in a low density gas stream are described. The supersonic stream had a mean free path as great at 4 cm, and the drag forces were small. A drag balance was adapted from an electrical analytical balance to measure forces up to 70 dynes with less than 1- percent error. With this balance, the drag of spheres was measured for the Knudsen number range from 1.0 to 5. The freedrop trajectory method yielded drag coefficients in the range of Knudsen numbers from 2.5 to 30. These tests demonstrated the feasibility of making accurate drag measurements under the free-molecule conditions that can be generated by exhausting a gas into a cryogenically pumped vacuum chamber.

Subject Categories:

  • Aerodynamics
  • Fluid Mechanics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE